The present invention is based upon the observation that oxygen can have a quenching effect on the molecular luminescence of various chemical compounds and that this effect may be employed in mapping or imaging oxygen concentrations of body portions of animals. Information about the distribution and concentration of oxygen is extremely useful in that it is indicative of tissue structure, anomalies, defects and diseases. The reader is referred to the above-cited U.S. Pat. No. 4,947,850 for further discussion of the background of the present invention.